Mercury switch



y 8, 1934- I L. L. BARKER 1,957,438

MERCURY SWITCH Filed June 21, 1930 Patented May 8, 1934 MERCURY SWITCH Lester L. Barker, Elkhart, Ind., assignor, by mesne assignments, to The Adams & Westlake Company, Chicago, 111., a corporation of Illinois Application June 21, 1930, Serial No. 462,777

6 Claims.

My invention relates to mercury switches and to the method of making the same, and. generally to sealed-containers of all types.

One object ofmy invention is to devise a meth- 0d of making mercury switches in which the electrodes are attached to the lead-in wires after the sealing of the latter in and through the wall of the switch envelope, thereby avoiding the subjecting of the electrodes to the deteriorating and oxidizing effects of the heat during the sealing operation.

A further object is the devising of a method of the foregoing character in which the manner of attaching the electrodes does not substantially alter their original condition, so that it is possible to use'pure metals that have been predegasified of deleterious materials with an assurance that the preadapted state of the electrodes will remain unaffected after the making of the switch is completed with a resulting more efficient operation of the device and a lengthening of its useful life.

A further object is to devise a method of making sealed containers generally which incorporate therein conductors having communication with an external source of electricity through lead-in Wires sealed through the wall of the container,

the junction of the conductors and wires within the container being either effected in a simple mechanical manner, or in the event that Welding or some other mode of attachment involving the use of heat is employed, their union is accomplished in an atmosphere of an inert gas such as hydrogen or helium, thus preserving the original characteristics of the conductors and preventing the formation of a film of oxide thereon.

A further object is the provision of a mercury switch in which the requisite native properties of the electrodes and/or such additional and desired characteristics as may be initially imparted thereto, prior to the making of the switch, are substantially preserved in the completed device.

Present methods of manufacturing mercury switches comprehend the attachment of the electrode to the lead-in conductors by welding, swedging, or some other mode of securement generally involving the use of heat, prior to the sealing of the conductors in and through the Wall of the switch container. which is generally a glass envelope, this operation also requiring the use of heat. In certain types of switches, the electrodes are specially manufactured, or are subject to a variety of'treatments-with a view of improving the operative qualities of the switch for indicated purposes. For example. the electrodes are frequently subjected to a process of degasification for the purpose of removing all gaseous traces therefrom which in the operation of the switch might otherwise be emitted as a cloud into the container, or might interact with the gas fill of 6 the switch with the same undesirable result, or might react chemically with the mercury to form slag or film deposits on the interior surface of the container. In addition, other electrodes may require some degree of hardness, or a special type of crystalline structure in order to provide for a uniform temperature condition during arcing between the electrodes. However. all of these initially imparted or native properties are frequently either entirely destroyed or. so impaired through being subjected to heat during the sealing in of the lead-in conductors, that the functional characteristics of the switch are considerably affected and its useful life reduced. Specifically, under these conditions. an electrode which has been 76 previously degasified absorbs gas or acquires a film of oxide which must be removed, since the sealing of the lead-in conductors generally requires the presence of oxy en to thoroughly wet the conductors with the material forming the 80 switch container; if the electrode has been hardened, it becomes annealed; and, further, if originally embodying a definite crystalline structure, the latter is frequently completely destroyed or substantially impaired.

With a View of solving the problem presented by the above difficulties, the method described in the present application has been devised. In its practice, briefly, the method consists in the attachment of the electrodes to the lead-in conductors either in a simple mechanical manner reference being bad to the accompanying drawing, and the novel means by which said objects are eifectuated will be definitely pointed out in the claims.-

'In the drawing:

Figure 1 is a sectional elevation of a characteristic form of mercury switch showing the latter no as it appears during one phase of my improved method.

Fig. 2 is a view generally similar to that shown in Fig. 1, but showing the completed switch in circuit-breaking position.

The switch shown in Figs. 1 and 2 is intended merely as illustrative of switches of this general character and it will be understood that the method hereinafter described may be modified as may appear desirable depending upon the external shape of the switch, the disposition and number of the lead-in conductors employed, and other factors which are now common in this art. As illustrated, the switch comprises a container 10, which may be formed of glass or other suitable substance and in the type shown has a generally elongated shape, although the precise nature of the. latter forms no part of the present invention. However shaped, the container 10 will initially include an opening 11 communicating the interior thereof with the atmosphere and through some portion of the enclosure constituting the container, represented generically by the numeral 12 designating an end wall of the container 10, lead-in conductors 13 and 14 are sealed therethrough and are connected externally of the container to any suitable source of electricity by means of conductors 15 and 16, respectively. Within the container 10, the ends of the lead-in conductors 13 and 14 are threaded as at 1'7 and 18, respectively,.for the reception of electrodes 19 and 20, respectively, having threaded pockets 21 and 22, respectively, for receiving the threaded ends 17 and 18, respectively.

Except for the relation between the threaded ends 17 and 18 and the electrodes 19 and 20, which is intended to represent generically any desired manner of mechanically connecting the electrodes to the lead-in conductors, although, as presently noted, the electrodes may be attached by a heat operation under definite conditions, the details of construction of the remaining elements noted above form no part of the present invention, so that they may be arranged for the carriage of currents of any value and at any voltage over any desired period of time, the sealing of the lead-in conductors 13 and 14 within the end wall 12 being such as to prevent leakage at these points, and said conductors being formed of material that is characterized by substantially the same coefiicient of thermal expansion as the material forming the container 10, in accordance with standard practice. This container also encloses a body of mercury 23 which is shifted from end to end thereof as said container is tilted by any approved means, the position of the mercury in Fig. 2 indicating a circuit breaking position and it being understood that when the container 10 is tilted in the opposite direction, the mercury mass will move along the bottom of the container 10 until it bridges the space between the electrodes 19 and 20, thus completing the electrical circuit within the switch.

As above described, the type of switch shown in Fig. 1 has its container 10 formed initially with the opening 11 communicating the interior thereof with the atmosphere. Thereafter the lead-in conductors 13 and 14 are sealed through the end 12, or through such other portions of the enclosure constituting the container 10 as may be desirable, dependent upon the number and disposition of the lead-in conductors, and thereafter the electrodes 19 and 20 are threaded on the complementary shaped ends 17 and 18 of the conductors 13 and 14, respectively. The mounting of these electrodes on the ends of the conductors indicated can be effected by the application of a suitable tool operating through the opening 11. Subsequently, the manufacturing method of my improved switch proceeds according to accepted practice'in that the air content of the container 10 is suitably evacuated and may be replaced by some approved gas fill and the determined amount of mercury 23, followed by a pinching. of the opening 11 to assume generally the shape shown by the numeral 24 in Fig. 2, thus hermetically sealing the container 10 and completing the formation of the switch.

As an alternative mode of securing the electrodes l9 and 20, it is contemplated that they may be attached to the lead-in wires after the sealing of the latter to present the appearance generally indicated in Fig. 2, either by welding, swedging, or some other mode requiring the use of heat, provided the attaching is accomplished in an atmosphere of an inert gas, such as hydrogen, helium, or a gas which isequivalent in respect of the indicated characteristic. The result obtained by either style of attachment, so far as affecting the electrodes is concerned, is substantially the same, since in both cases, neither the degasified condition of the electrodes is changed nor is an oxide film deposited. The removal of this film now occasions considerable difliculty in the art.

As above indicated, the specific advantages of this method of manufacturing a mercury switch, or any sealed container in general, is that it is possible to accurately determine in advance the characteristics which each part of the device should embody in order to meet certain operating conditions, for the reason that at no time during the manufacture of the latter are the desired characteristics of the elements thereof endangered by any condition arising out of the application of heat. The process of manufacture is, therefore, considerably simplified and it likewise results in a more improved type of apparatus.

While I have shown one set of elements and combinations thereof for eifectuating my im proved mercury switch, it will be understood that the same is intended for purpose of illustration only and in no wise to restrict the device to the exact forms and structures shown, for many changes may be made therein without departing from the spirit of my invention.

I claim:

1. The method of. makingelectric switches of the fluid flow type which consists in forming a container with an opening communicating with the exterior, sealing conductors through the wall of said container, attaching an electrode to one or more of said conductors within said container subsequent to the sealing of the conductors, inserting the conducting fluid in said container and closing the opening thereof.

2. The method of making electric switches of the fluid flow type which consists in forming a container with an opening communicating with the exterior, sealing conductors through the wall of said container, threading an electrode on the portion of one or more of said conductors within said container, inserting the conducting fluid in said container; andclosing the opening thereof.

3. The method of making electric switches of the fluid flow type which consists in forming a container with an opening communicating with the exterior, sealing lead-in conductors through the wall of said container, subsequently attachof said conductors within said container in an atmosphere of an inert gas, inserting the conducting fluid in said container, and closing the opening thereof.

4. The method of making electric switches of the fluid flow type which consists in forming a container with an opening communicating with the exterior, sealing lead-in conductors through the wall of said container, subsequently attaching an electrode to the portion of one or more of said conductors within said container in an atmosphere of hydrogen gas, inserting the conducting fluid in said container, and closing the opening thereof.

5. The method of making electric'switches of I the fluid flow type which consists in forming a container with an opening communicating with the exterior, sealing conductors through the wall of said container, mounting an electrode on the portion of one or more of said conductors within said container and retaining said electrode in position by portions thereon interlocking with other portions on said conductors, inserting the conducting fluid in said container, and closing the opening thereof.

6. The method of making electric switches, of v the fluid flow type which consists in forming an elongated container having an end wall and an opening remote therefrom and communicating with the exterior, sealing conductors through the wall, attaching an electrode to one or more of the conductors within the container subsequent to the sealing of the conductors, inserting the conducting fluid in the container and closing the opening thereof. v

LESTER L. BARKER. 

